There are presently available on the marketplace many forms of multi-bit screwdrivers where the several bits are contained within the hollow handle. When it is desired to use a particular bit, the handle is opened by unscrewing a cap for the handle and selecting the needed bit. The selected bit is then placed in the chuck at the other end of the handle for use. Unfortunately this system results in loss of bits because the bits are not retained with the screwdriver handle.
To overcome this problem, many screwdriver configurations have been suggested. For example, Butler, U.S. Pat. No. 3,405,749, discloses a multi-chambered tool holder. Several bits are held in the chambers in the handle. A truncated cone is provided at the end of the handle with a disc portion. The disc has a figure 8 shaped slot. When the disc is aligned with an end of one of the chambers in the handle, a bit can be extracted downwardly through the cone and inserted in the chuck portion of the handle. Due to the shape of the cone, the bits used in the system are presumably very short. Obviously with short bit arrangements, they do not lend themselves to many applications since a short bit makes it difficult to get into cramped places. In addition in order to negotiate the turn with the bit, most likely the hole 42 in the cone is enlarged which will probably allow the bit to fall out through the cone, thus a feature of retaining the bits in the driver is not provided.
An approach to retaining the bits in the screwdriver at all times is disclosed in U.S. Pat. No. 3,194,286. In that arrangement, the handle has a magazine of several bit configurations. By rotating the tapered lower portion 12, a desired bit may be selected. A chuck 14 is provided at the base of the tapered portion which secures the screwdriver bit. The bits are retained in the chuck by way of a rod extending through the chuck device to hold the bit in the chuck.
Another multi-chamber tool handle arrangement is disclosed in U.S. Pat. No. 3,006,395. The selected bit travels downwardly through a central channel in the handle and chuck portion, where the selected bit can be secured in the chuck. Another more complex arrangement to accomplish the same purpose is disclosed in U.S. Pat. No. 2,765,013 where linkage mechanisms are used to extend the desired bit beyond the handle. Another complex arrangement for a multi-chamber screwdriver is disclosed in U.S. Pat. No. 3,753,455 where the desired bit may be extracted from the handle and extended from a chuck portion. All of these arrangements require slanting the bit for purposes of selection and extension. Due to extended use of such tools as they become dirty and corroded, the smooth operation of the tool may be lost.
A direct extraction of the bit from a multi-bit handle is disclosed in U.S. Pat. Nos. 512,911 and 4,241,773. Unfortunately with these arrangements, the bit is off centre relative to the central axis of the handle resulting in an eccentric motion when the screwdriver is used. Thus the tool can only be used for the simplest of jobs.
The multi-bit screwdriver, according to this invention, overcomes a number of the above problems in providing a structure which is durable, easy to operate and is readily manufactured by injection molding of plastics.